Sudanese-born mother who put four of her seven children into her Toyota Kluger SUV, drove to a park in Melbourne’s outer west and plunged the vehicle into the depths of Lake Gladman will spend at least the next two ­decades in jail for murder and ­infanticide.

Akon Guode stood on the banks and did nothing on April 8, 2015, as emergency services tried to rescue and revive one-year-old Bol, four-year-old twins Hanger and Madit and six-year-old Aluel from the bottom of the lake in Wyndham Vale.

Her three youngest children died at the scene.

Judge Lex Lasry described Guode’s actions as “foreign and unthinkable” yesterday as he sentenced the 37-year-old in the Victorian Supreme Court to 26 years and six months behind bars, with a non-parole period of 20 years.

Guode, who moved to Australia from South Sudan in 2008 after the murder of her husband during civil war unrest, will most likely have her visa revoked, leading to her deportation at the end of her sentence.

In his remarks yesterday, Justice Lasry said he took the woman’s difficult personal circumstances into account when determining his sentence, but Guode’s was a crime that “tests the sympathy and compassion of the community”.

“Notwithstanding the various personal, historical and psychological pressures you were under at the time, which I acknowledge were significant, the real reason for your actions of this day are … a tragic mystery and have not been explained by you,” he said.

The court was told Guode was being chased by debt collectors, dealing with depression, and feeling isolated from her community at the time of the offence.

The sentencing hearing was temporarily adjourned as the mother wailed and sobbed during Justice Lasry’s remarks.

“In my opinion, your actions were a product of extreme desperation rather than any form of vengeance of a kind that has arisen in other cases of parents killing their children,” Justice Lasry said. But he was “by no means sure” she was remorseful for the actions.

During the trial, the court heard Guode had to make three deliberate turns to drive the car into the water from the road, illustrating “some level of planning and contemplation”, although Guode maintains she did not intend to kill the children.

One witness who called triple-0 at the time said she saw Guode leaning out the window and screaming after the car hit the water, while a baby was seen floating on its back and trying to keep its head up, struggling to breath.

After she drove the car into the lake, Guode denied she had done it on purpose, claiming she had suffered from a dizzy spell.

The local Sudanese community rallied around the mother after the children’s deaths, holding ­vigils and raising money for the children’s funerals.